Changing directories during the test breaks file loading when ran by itself

actionpack/test/abstract_unit.rb

@@ -51,6 +51,7 @@ I18n.backend.store_translations 'pt-BR', {}
 ORIGINAL_LOCALES = I18n.available_locales.map {|locale| locale.to_s }.sort
 
 FIXTURE_LOAD_PATH = File.join(File.dirname(__FILE__), 'fixtures')
+FIXTURES = Pathname.new(FIXTURE_LOAD_PATH)
 
 class ActionController::IntegrationTest < ActiveSupport::TestCase
   def self.build_app(routes = nil)

actionpack/test/controller/new_base/render_file_test.rb

@@ -1,7 +1,6 @@
 require 'abstract_unit'
 
 module RenderFile
-  
   class BasicController < ActionController::Base
     self.view_paths = File.dirname(__FILE__)
 
@@ -44,7 +43,7 @@ module RenderFile
     end
 
     def without_file_key_with_locals
-      path = File.expand_path('../../fixtures/test/render_file_with_locals.erb')
+      path = FIXTURES.join('test/render_file_with_locals.erb').to_s
       render path, :locals => {:secret => 'in the sauce'}
     end
   end
@@ -52,15 +51,6 @@ module RenderFile
   class TestBasic < SimpleRouteCase
     testing RenderFile::BasicController
 
-    def setup
-      @old_pwd = Dir.pwd
-      Dir.chdir(File.dirname(__FILE__))
-    end
-    
-    def teardown
-      Dir.chdir(@old_pwd)
-    end
-    
     test "rendering simple template" do
       get :index
       assert_response "Hello world!"
@@ -106,5 +96,4 @@ module RenderFile
       assert_response "The secret is in the sauce\n"
     end
   end
-  
 end